Sensitizing silver halide emulsions



Patented May 7, 1940 UNITED STATESi lPATlazN'rv OFFICE 2,199,542 SENSITIZING SILVER HALIDE EMUISIONS Walter Knig, Dresden, Germany, assignor, by mesne assignments, to General Aniline & Film Corporation, New York,l

Delaware N. Y., a corporation of Original application July 19, 1934, Serial No.`

Divided and this application August 16,1935, Serial No. 36,555. In Germany July 17 claims.

My present `invention relates to sensitizing -silver halide emulsions. It is a division of my copending application Ser. No. r[36,131 led July 19, 1934, Patent No. 2,158,287, issued May 16, 1939.l

One of its objects is the provision of silverV halide emulsions sensitized with new sensitizers.

with a cycloammonium salt containing a reactive methyl group', or with a corresponding methylene base, in the presence of a condensing agent.

In this. manner there are obtained dyestuis which may be presumed to correspond with the `general formula A Further objects will be seen from the detailedl specification following hereafter.

Reference is made to the accompanying drawing in which Figure 1 is a diagrammatic representationof thespectogram of the silver-halideemulsion sensitized with a nonamethlnecyanine dyestuii. Figure 2 shows the spectogram of the silver-hallde-emulsion sensitized with a nonl dyestu's whose polymethine chain contains at :amethinecyanine dyestu,v while Figure 3 is the representation of the spectogram of the silverhalide-emulsion sensitized with an undecamethinecyanine dyestufl'.

According to the present invention polymethine least seven carbon atoms and contains as a. sub. stituent an acyloxyor alkoxy-group are made by condensing a polymethine dyestuil of the general formula Rg R l wherein i 1 l R1 Rx N/ and N/ \Ba \Ra represent residues of secondary or primary amino-groups or residues of secondary cycloamlnes R5 represents acyl (including sulfoacyl) or alkyl, X represents halogen or any acid residue and n represents 0, 1, 2 or 3,

In the formulae A and B r Y and Z represent sulfur, selenium, oxygen or a group (Y and Z may be the same or dierent radicals) f R1, Re'. R3, R4 represent hydrogen, alkyl, alkoxy, aryl, carboxyl or alkyl-carboxyl, acyl or in some cases R5 represents acyl, aracyL alkylor aryl-sulfonyl or alkyl; Re and R1 represent alkyl or aryl;

Ra and Re represent alkyl, aryl, aralkyl or hydrogen;

X represents an inorganic or organic acid resi' due, for example Cl. Br, I, C104, CH:- CaHl-SOa; GHz-504, (32H5-S04; and

'n represents 0, 1, 2 or 3.

In carrying out the invention. there may be used quaternary salts vof all heterocyclic basesV containing areactive methyl group or the corresponding methylene bases, particularly the quaternary salts of monoand polynuclear thiazoles, selenazoles and of 2- and 4-methylquinolines, pyridines, pyroleines and indolenines. Examples of suitable condensing agents are pyridine bases, aliphatic bases, for example, triethanolamine, alcohol and piperidine, alcohol' and sodium acetate, acetic anhydride alone or together with sodium acetate or potassium acetate.

The polymethine dyestuffs of the general formula R1 R1 /N-CH=CHCH= IJ-(CH=CH),.-CH=N\ x R2 0K3 R2 constituting intermediate products for the manufacture of the dyestuifs of formulae A and B can be made by reaction between secondary or primary amines and furfurol lor its vinylenehomologues such as furfur-acrolen and so on, followed by acylation (such as benzoylation) or alkylation of the product.

The polymethine dyestuis made` in accordance with the invention are excellent photographic sensitizers for the infra-red region of the spectrum; as compared with the hitherto known sensitizers for the infra-red, their range of sensitization is considerably displaced towards the long wave region. In particular, with these dyestuffs it is possible to produce photographic silver halide emulsion layers which are sensitive to wave lengths exceeding 1000 an.

The dyes are obtainable according to the desired solubility in form of the bromide, iodide, perchlorate, etc. For sensitizing a silver halide emulsion, they are used in a quantity, such as is usual for the known sensitizing dyes. This quantity may amount to about 0.5 to 1.5 milligrams per kilo of emulsion ready for being cast which contains about 9 per cent of gelatin, 4.5 per cent. of -silver halide and the rest water. However, the

, invention is not limited to the quantities just inalcohols, for instance, methyl or ethyl alcohol which may be used anhydrous or diluted with Water. The dyes are applied to the emulsion 'during any stage of its production; however, they are preferably added to the finished emulsion before casting.

The dyes may likewise be incorporated in the emulsion b y bathing the nished photographic material in abath in which the dye is dissolved. Such a treatment may be as follows: The photographic material to be sensitized is bathed in a solution containing 1 milligram of bis-[5.6-dimethoxy 3-ethyl-benzthiazole-(2) l-e-acetyloxy nonamethine cyanine perchlorate in 1000 cc. of an aqueous solution of methanol of 50 per cent. strength for about 5 minutes. The material is then dried, whereupon it is ready for use.

The following examples illustrate the invention:

Example 1.Manufacture of the dyestuff bisl [3-methyl-6-phenyl benzthiazole- (2) l-e-acetyloxy-heptamethinecyanine perchlorate.

There is rst prepared the pentamethine dyestu of the formula v o-CocHa CtHs CtHa \N=cH-GH=CH- v:cH--Ny CHS C104 CH3 by heating the Schiffs unstable pentamethine perchlorate from furfurol and 2 molecular proportions of monomethylaniline which forms pure red solutions and is described more precisely by Ebert (Dissertation Dresden 1913) in about five times its weight of acetic anhydride for about 1 hour at about 80 C. The new dyestui is then precipitated with ether and may be recrystallized from acetic anhydride. In comparison with the red dyestui containing a free hydroxyl group, which is quite useless for dyeing purposes, the

'neW product is very stable; it dyes tanninmordanted cotton reddish-yellow, that is to say, almost exactly the same shade as the analogous pentamethine dyestui unsubstituted at the mesochrome. Accordingly its absorption bands are4 almost exactly in the same position as those of the-latter.

The pentamethine dyestuff` can also be pre- 4 pared by the action of acetyl chloride in presence of pyridine. Thus, for example, the chloride corresponding to the pentamethine dyestuf can be obtained by dissolving the red chloride of the monomethylariilinefurfurol dyestuff in about 20 parts of pyridine, cooling the solution to -20-C., adding somewhat more than l molecular proportion of acetyl chloride and subsequently introducing the reaction solution into-ice water saturated with sodium chloride and acidied with hydrogen chloride.

For the manufacture of the heptamethine dyestuif (heptacarbocyanine dyestuff) of the probable formula:

1 molecular proportion of the pentamethine dyestuif perchlorate of Formula I is dissolved in about 20 times its -weight of pure pyridine and combined at ordinary temperature with about 2.5 molecular proportions of the quaternary salt of the formula:

p fe.

III

(obtainable from para-aminodiphenyl by means of S2Cl2 according to the Herz method by way of the ortho-mercapto derivative). The solution.

which is at first orange, becomes bluish green and ilnallyreddish-blue. After about half an hour,

the solution is mixed with one and a. half times its volume of ethanol, whereupon the -dyestufl' precipitates in the form of crystals having a green lustre. The green solution of the dyestuf! in methanol has an absorption maximum at about 740 'Mt and a second band at about 430 mi.

Ca S.

[3-methy1-6-pheny1-4-chloro benzthiazole- (2) le-acetyloxy-heptamethine cyanine perchlorate of the general formula This dichloro-derivative of the dyestuff represented by Formula 1I can be obtained in a manner analogous to that described in Example 1 from the Quaternary salt of the probable formula:

CoHs- S c-CH, o-soa-oorn N oi (11H3 (This salt can be synthesized from a by-product obtained in the preparation of the salt represented-by Formula-III in a manner analogous to that by which the said salt is made.)

The main band of the new dyestufl", which forms olive-green crystals, is displaced by a few pp bathochromically as compared with that of the dyestuff II.

A ne grained silver bromide emulsion of middle sensitivity and containing about .2 per cent oi silver iodide shows a maximumof sensitivity at about 830 ,la when sensitized with the dye.

Example 3.-Manufacture of thevdyestui bis- [Srmethyl-G-phenylnlbenzthiazole- (2) l -e-acetyloxy nonamethine cyanine chloride.

The heptamethine dyestui of the formula about 1 molecular proportion of acetyl chloride.

The product is worked up in the manner described in Example 1. The dyestuii salt is thus obtained as violet-red needles having a blue lustre,

which dissolve in alcohol to a blue-red solution and dye tannin-mordanted cotton violet.

Co S

i ton reddish-blue.

Ain a similar manner by causing pyridine fandacetic anhydride to act onthe perchlorate-offline dyestufl containing free hydroxyl.v

For the manufacture of the dyestuff oftlie 'foldv lowing probable formula:.

1 molecular proportion oi' the violet heptamethine dyestui chloride VI is caused to react in the manner already described with about 2.5

molecular proportions of the salt 111. The color of the solution changes from violet to olive green. After a short time the whole is diluted with an equal volume of ethanol, whereupon the dyestui precipitates in the form of small grey-green crysals. It dissolves in pyridine to a faintly green solution having an absorption maximum between 900 and 1000 ML; sharp, only slightly persistent bands are present in the visible spectrum at about 480 and 455 im.

A fine grained silver bromide emulsion of middle sensitivity and containing about 2 per cent of silver iodide is sensitized to waves from about 750 to 1000 mi with a maximum at about 925 pp.

Example aLl-Manufacture of the dyestuff bis- [3-methyl-6-phenyl benzthiazole- (2) l -f-benzoyl nonamethine cyanine chloride.

The heptamethine dyestu of the followingrv probable formula:

c-o ci o-c VIII is first prepared by shaking 1 gram of the greenblue dyestuff chloride obtainable from furfuracrolein, tetrahydroquinoline and hydrochloric acid according to the process of Knig (Journ. prakt. Chem. (2), vol. 88, page 216) with 15 times its weight of cooled pyridine until it is completely dissolved, whereupon the hydroxyl group is benzoylated by gradual addition of 1 molecular proportion of benzoyl chloride. The

.dyestu can be isolated in theusual manner by pouring the reaction mixture into a saturated solution of sodium chloride acidied with hydrochloric acid land may then be recrystallized from alcohol or acetone. It forms small needles having a blue lustre and dyestannin-mordanted cot- The pure blue chloride VIII is then caused to react in solution in pyridine with the salt III.

ingprobable formula: v

The corresponding perchlorate can be obtained in the form of small green-scid. glittering crystais whose absorption properties are very similar to those of dyestuff VII.

A iine grained silver bromide emulsion of middle sensitivity and containing about 2 per cent of silver iodide is sensitized to Waves from about 750 to 1000 by. with a maximum at about 925 m5.

Example 5.-Manufacture of the dyestutl bis`l [3-methyl-6-phenyl lbenzthiazole- (2) l -e-acetyloxy undecamethine cyanine perchlorate.

'I'he nonamethine dyestuff of the following formula is first made in the ,following manner: By condensation of 1 molecular proportion of streptodivinylene furfurol (5-(a-furyl) pentadienal- Ca \C104 (1)) (cf. Knig, Berichte, 1925, Vol. 58, page 2564) with 2 molecular proportions of tetrahydroquinoline` and 1 molecular proportion of perchloric acid in solution in cooled acetone, there is. rst obtained the non-acetylated pure green dyestuff corresponding with the acetylated dyestui of Formula IX. It is converted into the acetylated dyestui IX by treatment with 'acetic anhydride in solution in pyridine, the reaction mixture being strongly cooled during the operation with carbon dioxide. snow and ether. The dyestui is then precipitated from the blue-green solution by the addition of ether in the form of small ne needles which dissolve readily in alcohol to a solution having the color of malachite green.

The undeca-methin'e cyanine dyestuff of the probable formulaz c; \c1o. jl" .x

is obtained in the form of green-black microcrystals by causing the salt III to react in the manner described in Example 1 with the streptononamethine dyestui salt of Formula IX and then diluting the solution, whose color changes from bluegreen` through green to pure yellow, with ethyl alcohol. In spite of its peculiar;V dark superficial color, the product dissolves in pyridine to a pure yellow solution, that is to say, it is a pronounced dyestul of higher order. The absorption maximum of the solution in pyridine has not'yet been exactly determined, but lies above 1000 ML; in the visible part of the spectrum, bands can be observed at about 525, 489 and 459 mi.

A fine grained silver bromide emulsion of middle sensitivity and containing about 2 per cent of silver iodide is sensitized to waves from about 950 to 1150 mi with a maximum at about 1050 an.

Example 6.-Manufacture of the dyestuif bis- [3.5dimethyl benzselenazole (2) l-e-acetyloxynonamethine cyanine perchlorate of the probable formula CHI Hx XI The dyestui can be obtained in the usual manner from the violet heptamethine dyestui perchlorate VI and the l1.2.6-trimethyl-benzselen azolium bromide described by Julius (Dissertation, Dresden 1928), in the form of lsmall dark crystals. The secondary bands of the greenish solution of the dyestui in a mixture of pyridine and methanol lie in the visible region at about 476 and 444 mi.

A fine grained silver bromide emulsion of middle sensitivity and containing about 2 per cent of silver iodide shows a maximum of sensitivity at about 935 up. when sensitized with-the dye.

Example 7.-The dyestuff bis-[l-dimethyl-3- methyl-indole-(2) l-e-acetyloxy nonamethine cyanine chloride of the probable formula XII is' obtained by causing about 2.5 molecular proto react in pyridine solution with 1 molecular proportion of the dyestuff xm .f which can be obtained analogously to the dyestufl VIII from turfuracrolein with subsequent acetylto green, whereupon addition oi alcohol precipitates small greenish-black crystals having a main absorption in the infra-red and secondary bands in the visible spectrum at about 475 and 442 yp..

A ne grained silver bromide emulsion of middle sensitivity and containing about 2 vper cent of silver iodide is sensitized to waves from about '750 to 950 an with a maximum at about 900 pp.

Example 8.--For producing bis-[3-ethy1-5-6- dimethoxy benzthiazole (2) l-e-acetyloxy nonamethine cyanine perchlorate corresponding with the formula there is prepared from a-furylacroleln, perchloric acid and tetra-hydroquinoline the Oxy-azomethine 'dyef which is acetyled with somewhat more than the calculated amount of acetic anhydride in pyridine solution.

2 grams of the acetyl compound corresponding probably with the formula are dissolved in 40 cc. of dry pyridine withv 2 grams of 2methy15.6dimethoxybenzthiazole diethylsulfate. The mixture assumes slowlya dark-blue color. After some time, there are added 2- cc. of triethanolamine, the mixture is stirred and the color changes into green. Then there are added about 60 cc. of alcohol and after continuing with stirring the dye separates in copper-colored crystals.

A ne grained silver bromide emulsion of middle sensitivity and containing about 2 per cent of silver iodide is sensitized to waves from about 600 to 1100 y with a maximum at about 950 mi.

Example 9.-1 gram of the azomethine compound prepared as described in Example 8 and corresponding with the iormula Q 000011:",A Q

vInn.

is dissolved with 2 of lepidine dimethyl-i 2,199,542 ation. The color of the reaction mixture changes sulfate in about 20 cc. of pyridine. The mixture gradually assumes a green color. Now, there are added 1 cc. of diethylamine, and after al short period of time about 20 cc. of alcohol. After some time the bis-[l-methyl-quinoline- (4)]-e-acetyloxy nonamethine cyanine perchlorate corresponding probably with the formula Hz H: Ha Hz (preparation according to Example 8) is dissolved.with 0.8 gram' of 2-methyl--naphthiazole diethylsulfate in about 30 cc. of pyridine. After standing 1 hour, the solution which has assumed a blue--green color, is mixed with about 40 cc.

of alcohol, whereafter an intermediate product corresponding probably with the formula separates. 0.5 gram of this intermediate product are dissolved with the same amount of 2-methyl- -ethoxybenzthiazole diethylsulfate in 20 cc. of pyridine while shortly boiling. On the addition of alcohol thedye bis-[3-ethyl-naphtho 4.5: 2'.1thiazo1e}] [3-ethyl--ethoxy-benzthiazole- (2)]-e-acetyloxy nonamethine cyanine perchlorate corresponding probably with the formula separates in the form of crystals.

` A ne grained silver bromide emulsion of middle sensitivity and containing about 2 per cent of silver iodide is sensitized to waves from about 650 to 1050 pp. with a maximum at about 940 nu.

Example 11.--For producing the dye corresponding with the formula a-furylpentadienal (prepared according to K- nig, Ber. 58, 2564) is brought to reaction with perchloric acid and tetrahydroquinoline in methanolic solution to form the azomethine dye and the latter is acetylated with somewhat more than the calculated amount of acetic anhydride in pyridine solution.

1 gram of the acetyl compound corresponding probably with the formula chlorate corresponding to the formulay separates gradually in the form of a black crystal powder.

is dissolved with the same amount of 2-methyl- 5.6-diethoxybenzthiazole-diethylsulfate in 15 cc. of pyridine. The mixture assumes gradually a dark-blue color. If, after standing for 2 to 3 hours, the mixture is mixed with alcohol the intermediate product corresponding with the formula A ne grained silver bromide emulsion of middle sensitivity and containing about 2 per cent of silver iodide is sensitized to waves from about 750 to 1050 mi with a maximum at about 930 M.

Example 13.-The azomethine compound obtainable according to Ex.`8 from furfurolacrolein, perchloric acid and tetrahydroquinoline is acetyseparates, is ltered and dissolved immediately with 1 gram of 2-methyl5.6diethoxybenzthiazole diethylsulfate while warming cautiously. After cooling there are added about 15 drops of triethanolamine, whereupon the solution becomes green to yellow-green. On the addition of about 30 cc.'of alcohol the bis-[3-ethyl-5-6- diethoxy-benzthiazole- (2) l-y-acetyloxy undecamethine cyanine perchlorate is precipitated in the form of a copper crystal powder.

A ne grained silver bromide emulsion oi middle sensitivity and containing about 2 per cent of silver iodide is sensitized to waves from about '750 to 1150 mi with a maximum at about 1050 up..

Example 12.-When Working according to the method described in Ex. 11 and'using quinoldine dimethylsulfate instead of the quaternary ammonium salt of 2-methy1-5.G-diethoxybenzthiazole there is obtained the intermediate product corresponding probably with the formula OCOCH:

in the form of green-black crystal powder. rIthis intermediate product is dissolved in pyridine lated with somewhat more than the calculated amount of butyric anhydride in pyridine solution, 0.5 gram of the dye obtained and corresponding with the formula perchlorate separates after some time in the form of bronze-colored crystals.

A iine grained silver bromide emulsion of middle sensitivity and containing about 2 per cent of silver iodide is sensitized to waves from about '150 to 1000 1w with a maximum at about 915 pp.

What I claim is:

1. A photographic material comprising a silver halide emulsion containing a polymethine dye selected from the class consisting of those' while cautiously warming, and after cooling corresponding with the general formula Rx I B -i l r' .-i/ -ort=oH-oB'-on (on-oH).=-oH-on= R-f if Rl BI there are added to the mixture a few drops of diethylamine. The dark-blue solution immediately becomes green to green-yellow. After about 10 minutes alcohol is added to the mixture whereupon the formed bis-[l-ethyl-quinoline- (2)1-'y-acetyloxy undecamethine cyanine per- Y and Z stand for the members oi the group consisting of S, Se, CH=`CH and R1, R2, R3, R4 stand for the members of the group consisting of H, alkyl, alkoxy, aryl, carboxy, alkyl-carboxy and acyl;

and

stand for the members of the group consisting of phenylene and naphthylene radicles;

R5 Vstands for acyl; u Q

Re and Rv stand for a memberjofthezgroup consisting of alkyl and ary1 Y A 7 Re and Rs stand for a member of the group consisting of H, alkyl, aryl and aralkyl;

X stands for an anion capable of precipitating the dye;

n stands for one of the group consisting of 0, 1, 2 and 3 and those isomers in which Y and Z are -CH=CH and in which at least one nucleus is linked to the methine chain in 4- position. i 2. A photographic material comprising a silver halide emulsion containing bis-[3-ethyl-5-6- dimethoxy-benzthiazole- (2) l-e-acetyloxy nonamethine cyanine perchlorate.

3. A photographic material comprising a silver halide emulsion containing bis-[B-ethyl-5-6- diethoxy-benzthiazole- (2) l-e-acetyloxy undecamethine cyanine perchlorate.

4. A photographic material comprising a silver halide emulsion containing bis- [3-5-dimethylbenzselenazole- (2) l-E-acetyloxy nonamethine cyanineY perchlorate.

5. A photographic gelatino-silver-halide emulsion containing a bis- [N-alkyl-benzthiazole- (2) `le-acetyloxy nonamethine cyanine perchlorate.

6. A photographic silver-halide emulsion containing a sensitizing nonamethinecyanne salt in which the hydrogen atom of one of the methenyl groups'of the nonamethenyl chain is replaced by an acyloxy group.

7. A photographic silver-halide emulsion containing a sensitizing nonamethinecyanine salt in which the hydrogen atom on the central methenyl group of the nonamethenyl chain is replaced by an acyloxy group.

8. A photographic-gelatino-silver-halide emulsion containing a bis-[N-alkyl-benzthiazole-(2) le-acetyloxy-undecamethine cyanine perchlorate.

9. A photographic silver-halide emulsion containing a sensitizing undecamethinecyanine salt in which the hydrogen atom of one of the methenyl groups of the undecamethenyl chain is replaced by an acyloxy group.

10. A photographic silver-halide emulsion containing a sensitizing undecamethinecyanine salt in which the hydrogen atom on the fifth methenyl group of the undecamethenyl chain is replaced by an acyloxy group.

11. AA photographic material comprising a gelatino-silver-halide emulsion containing a sensitizing nonamethinecyanine salt, in which the hydrogen atom of one of the methenyl groups of the nonamethenyl chain is replaced by an acyloxy group.

12. A photographic gelatino-silver-halide emulsion containing a sensitizing thianonamethinecyanine salt, in which the hydrogen atom on the central carbon atom of the nonamethenyl chain is replaced by an racyloxy group.

13. A photographic material comprising a gelatino-silver-halide emulsion containing a thianonamethinecyanine salt in which the hydrogen atom of the central methenyl group of the nonamethenyl chain is replaced by an acetoXy group.

14. A photographic material comprising a gelatino-silver-halide emulsion containing a sensitizing undecamethinecyanine salt, in which the hydrogen atom of one of the methenyl groups of the undecamethenyl chain is replaced by an acyloxy group.

15. A photographic gelatino-silver-halide emulsion containing a'sensitizing thiaundecamethinecyanine salt, in which the hydrogen atom of one of the methenyl groups of the undecamethenyl chain is replaced by an acyloxy group.

16. A photographic material comprising a gelatino-silver-halide emulsion containing an undecamethinecyanine salt in which the-hydrogen atom of the fifth methenyl group of the undecamethenyl chain is replaced by an acyloxy group.

17. A photographic material comprising a gelatino-silver-halide emulsion containing a thiaundecamethinecyanine salt in which the hydrogen atom of the fifth methenyl group of the undecamethenyl chain is replaced by an acetoxy group.

WALTER KNIG. 

